From 3e5b16c2cf3d2d105f28f7efe143445808053d3d Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Sun, 20 Apr 2025 09:46:11 +0100
Subject: [PATCH] SDL2_gfx: fix underlinking against `-lm`

Without the change `freeciv_sdl2` fails to detec `-lSDL2_gfx` as
https://hydra.nixos.org/build/294735307:

    checking for rotozoomSurface in -lSDL2_gfx... no
    configure: error: specified client 'sdl2' not configurable (SDL2_gfx is needed (www.libsdl.org))
---
 pkgs/by-name/sd/SDL2_gfx/package.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/by-name/sd/SDL2_gfx/package.nix b/pkgs/by-name/sd/SDL2_gfx/package.nix
index 4d6f6d77bbd7..5ae903baf1c2 100644
--- a/pkgs/by-name/sd/SDL2_gfx/package.nix
+++ b/pkgs/by-name/sd/SDL2_gfx/package.nix
@@ -38,6 +38,10 @@ stdenv.mkDerivation (finalAttrs: {
     "dev"
   ];
 
+  # Missing 'sincos()' implementation fails linking projects
+  # like 'freeciv_sdl2'.
+  env.NIX_LDFLAGS = "-lm";
+
   configureFlags = [
     (lib.enableFeature enableMmx "mmx")
     (lib.enableFeature enableSdltest "sdltest")